Greater interconnection between Scotland and England, as well as the development of probabilistic analysis will be needed over the next decade according to National Grid ESO.

This is the upshot of the operators Electricity Ten Year Statement (ETYS) for 2019, which follows much in the same vein as 2018’s statement.

In the foreword, Craig Dyke, the head of networks at ESO highlights the scale of the energy revolution. "The economic landscape, developments in technology, and consumer behaviour are changing at an unprecedented rate, creating more challenges and opportunities than ever for our industry.”

Interconnection forms one of the biggest recommendations within the statement, as it did last year. In particular, increases to wind generation in Scotland will mean greater connection with England is needed.

In the ESO’s Future Energy Scenario Two Degrees - within which the UK is able to limit climate change to within two degrees - the flow through the Scotland– England boundary is expected to reach 15.9GW. This is almost three times the current 5.7GW boundary capability.

Together with this, there is a potential increase of more than 6GW of low-carbon generation and interconnectors in the North of England, that will likely be an increase in transfer requirements in the Midlands. This will mean that the grid will have to be reinforced in this area.

This will be further compounded by up to 8GW of growth in wind power off the coast of East Anglia, and an increase in the number of interconnectors with Europe. If there is high wind energy generation in Scotland for example, the UK could be exporting power from Scotland through to England and then through to mainland Europe, leading to high power flows throughout the whole network that could strain the system.

Distributed generation will continue to challenge the network, with wind and solar power growing. New technologies such as electric vehicles, energy storage and heat pumps are also increasingly attached to the grid, complicating the requirements of the NETS, which is becoming driven more and more by conditions other than the winter peak.

In response to this greater mix, the ESO is changing its probabilistic approach to look at a broader range of potential conditions.

This will move the company on from its current probabilistic approach, which uses historical profiles as inputs to the Monte-Carlo simulator. This has previously worked when the system relied on fewer, larger and more balanced generation created by fossil fuels and nuclear power, as it used samples of likely background generation and demand conditions, to produce sequential hourly snapshots. These could subsequently be analysed and predictions made.

The new approach will combine the Monte Carlo sampling economic dispatch and a direct current power flow network assessor element. By using this new, year-round probabilistic technique, the ESO can look at a broader range of snapshots. This will allow it to identify a lot more network requirements than the traditional approach.

This is currently a pathfinder project of the operators, and won’t form part of the existing NOA process as it only accounts for thermal analysis at the moment. The ESO hopes to develop it throughout the next year, including techniques to calculate dynamic boundary capability, before providing proof of concept for the integration of probabilistic network analysis into NOA process in 2021.

The NOA is expected in January of 2020, after the ESO has assessed around 180 options including doing a cost-benefit analysis that can help the operator produced recommended options requiring expenditure next year as well as what will be delayed. At the time of writing, seven of these assessments have been started.

The ETYS provides a view of the requirements needed to meet future demands of the transmissions system, along with the capability of the National Electricity Transmission System (NETS) to meet them.

It is put together by combining the system operator's Future Energy Scenarios with NETS simulation models, in order to allow the ESO to analyse the most likely changes - and challenges - in the coming years.

It is a significant part of the National Grids planning process, allowing it to identify potential requirements. These are then assessed through the Network Options Assessment (NOA) process.